Flowable to plastic synthetic resin compositions based on poly-isocyanates are known, which are adapted to be applied by casting, painting, filling and the like, the compositions being capable of hardening or curing in the presence of water.
For example, a one-component system is disclosed in U.K. Pat. No. 1,064,841 which contains a polyisocyanate and a poly-aldimine or ketimine. The mixture must be stored with the absolute exclusion of water and has a very short processing time. In German publication 16 94 237 there is disclosed a polyisocyanate, the isocyanate groups of which are blocked, so as to effect curing in the absence of water at an elevated temperature. In addition, it is also taught in this reference that di- and polyenamines are as effective as cross-linking agents as poly-ketimines, but less sensitive to hydrolysis, which is an advantage relative to the shelf life of the compound. In German publication 21 16 882 the production of di- and polyenamines is described, indicating that the shelf life of mixtures consisting of polyisocyanates and polyenamines is about 9 months. Further, the use of mixtures containing di- or polyisocyanates and di- or polyenamines as potting, smoothing, plating or coating materials is taught in German publication 21 25 247. The mixture described therein has a shelf life of more than 9 months, with the proviso that moisture is absent. Curing is effected through the influence of moist air; water or water vapor.
In practice, however, it is disadvantageous that with mixtures of di- or polyisocyanates and di- or polyenamines the curing reaction is started immediately when the components contact moisture. If such a mixture is to be applied to large areas at higher degrees of air moisture, say at about 75 percent relative humidity and above, the curing will begin during application, that is, from the processor's standpoint, prematurely. On the other hand, the curing time is relatively long with low air moisture, at about less than 60% relative humidity. When curing is carried out with water or vapor, the curing will occur quicker, but also uncontrolled.
Known polyisocyanate/polyenamine mixtures have another disadvantage, that being that uniform curing of thicknesses of greater than about 0.1 mm may not be attainable. The moisture from the air, or water, or water vapor, can penetrate into the mixture only from the outside to the inside, so that with greater thicknesses, the reactive composition near the free surface will be cured to a greater degree than the inside surface, which will have an unfavorable effect on the properties of the cured product. Because of this, known polyisocyanate/polyenamine mixtures are in general unsuited for embedding, impregnating, coating of electrical structural members for insulation, etc.
The invention is therefore based upon the problem of removing the above-mentioned disadvantages and of providing a synthetic resin which will cure without moisture. Water is applied in an amount not exceeding that necessary for curing, and the water is uniformly distributed throughout the mass. Curing takes place within a predeterminable period of time.